Activists: Liberal and conservative advocacy groups have quickly gotten on message and into the fray over the nomination to fill the Supreme Court's swing-vote seat.

WASHINGTON - Minutes after Supreme Court Justice Sandra Day O'Connor announced her retirement, 24-year-old Georgetown University graduate Kristin Bateman rushed to her computer in People For the American Way's fifth-floor "war room" and hit the "send" button.

Through the miracle of instant messaging, nearly 2,000 of the liberal advocacy group's Washington volunteers received an e-mail urging them to rush downtown and start calling activists in battleground states.

Two hours later, the war room's 40 computer stations and 70 phones overlooking M Street N.W. were nearly full, and a conference table was packed with volunteers stuffing envelopes. At 1:20 p.m., pizza arrived. At 2 p.m., Ralph Neas, the group's president, took a break from the first of dozens of media interviews to give a pep talk.

"Everything we've ever believed in is at stake," he told the group of mostly young volunteers.

"If a right-winger replaces Sandra Day O'Connor, that right-winger can turn back the clock seven decades."

So began an Olympic battle between right and left that will define what promises to be one of the most polarizing Supreme Court nomination battles in history. Advocacy groups on both sides have been preparing for this moment since George W. Bush's election in 2000, filming commercials, amassing funding and hiring veteran political consultants, pollsters and legal experts to help swing public opinion their way in those critical first hours after a nomination.

"This is the opportunity conservatives were motivated to go out and vote for the president for," said Tony Perkins, president of the conservative Family Research Council, which plans to mobilize members of more than 20,000 churches nationwide to counter the efforts of Neas and his band of volunteers.

O'Connor's announcement Friday was like a starting gun, setting in motion a meticulously choreographed campaign that will be waged 24/7 through the Internet, cable talk shows, nightly news broadcasts and newspaper editorial pages in the weeks ahead.

With Republicans controlling Congress and the White House, optimism is high on the right. When news of O'Connor's retirement broke, staff members from Perkins' group were on the steps of the Supreme Court building, delighting in the prospect that President Bush could replace a justice they felt had repeatedly betrayed their values with someone who would vote their way on abortion, the separation of church and state and other issues.

The council and allied groups have hired constitutional law experts to help them make their case for a nominee in the mold of Justices Antonin Scalia and Clarence Thomas, the court's two most conservative voices.

But by early afternoon, the war room on the third floor of the council's building just west of the MCI Center - really nothing fancier than a conference room with a long wooden table - was starting to look inadequate.

"Really, the whole building's a war room right now," said Connie Mackey, the council's vice president for governmental relations.

The group expects to raise millions of dollars to buy television, radio, newspaper and Internet ads to further the cause and to send out direct mail and e-mail to supporters urging them to contact elected officials.

Mackey, a veteran of the Thomas confirmation battle, said conservatives have never been better prepared to fight for a nomination. With Thomas, and before him the failed nomination of Robert Bork, conservatives were caught off-guard and were outgunned by liberal groups. Not this time, she said.

"We're not going to see a `Borking' of any nominee who would be a constitutionalist," she said, meaning someone in the mold of Scalia or Thomas.

One conservative group, Washington-based Progress for America, has pledged to raise $18 million to support confirmation for whomever the president nominates. The group has already launched television, radio, print and Internet ads across the nation. Other groups are preparing rallies, marches and protests around Washington.

The three-year-old Committee for Justice, designed as an information hub providing expertise on judicial nominations for conservative groups, sprung into action at its Pennsylvania Avenue headquarters yesterday, sending out talking points and fielding dozens of calls from reporters.

The left has long had similar groups, but the Committee for Justice is the first conservative organization working full-time on judicial nominations, said its executive director, Sean Rushton. It has just four full-time staff members, but it serves to connect dozens of grassroots organizations dedicated to social, fiscal and legal conservative causes.

"Right now it's a lot of hurry up and wait," Rushton said. "It's a matter of getting all our information and materials all ready to go and into the right hands when eventually the nomination occurs."

The one thing that could deflate all the effort, some conservatives said, is if Bush chooses a more moderate nominee.